As a new energy source for vehicles, fuel cell is becoming a research hotspot, and the related technology of hydrogen supply is also becoming a research emphasis. With the advantages of high efficiency, large energy density, low noise and non-pollution, proton exchange membrane fuel cell is regarded as the next generation of power unit for vehicles which is mostly to replace internal combustion engine. Hydrogen, the fuel for proton exchange membrane fuel cell, does not exist in natural world and can only be transformed from other kinds of energy. However, the active chemical property of hydrogen makes it a problem for hydrogen storage. With the technology of auto-thermal conversion of diesel designed in the Invention, it can not only achieve zero-emission of the fuel cell, but also solve the problem of hydrogen source. Some reference patents (CN101142016B and U.S. Pat. No. 8,349,288) have provided a device and a method for homogeneous conversion of oil and oxygen as well as an approach and a method for auto-thermal conversion of methane, but they have given no overall scheme with fuel cell. With inadequate design for self-supply of hydrogen for fuel cell, the practical applicability needs to be further studied. The Patent conducts systematic study on diesel pyrolysis for generating hydrogen and provides a new overall scheme more feasible for self-supplied hydrogen of diesel. Generating hydrogen through electrolysis of water is only a method applied in a laboratory rather than in a vehicle. The Invention is designed to provide energy to achieve zero emission of fuel cell by achieving self-generated hydrogen for diesel vehicles.